School of Computer & Communications Engineering Universiti Malaysia Perlis (UniMAP) LABORATORY MODULE. Digital Systems 1 (DKT 122/3)

Transcription

1 School of Computer & Communications Engineering Universiti Malaysia Perlis (UniMAP) LABORATORY MODULE Digital Systems 1 (DKT 122/3) Semester 2 (2013/2014) Experiment 1: Introduction to Logic Gates

2 OBJECTIVES LAB 1: Introduction to Logic Gates 1. Ability to operate basic electronic components. 2. Ability to analyse and explain the IC datasheet configuration. 3. Ability to construct and demonstrate simple digital circuits. EQUIPMENTS & COMPONENTS 1. DC Power Supply (fixed 5V) 2. Oscilloscope 3. Multi meter 4. Broadboard 5. Integrated Circuits (IC) 6. Resistor (330 Ω) 3 unit 7. LED 4 unit 8. SPDT Switches 3 unit INTRODUCTION This module will introduce the students on the basic components on digital circuit buildings and observing logic IC operations. Basically the hardware to be used in this lab will be : 1. Breadboard 2. Toggle switches TTL ICs 4. LEDs 5. Resistors Afterwards, the students are required to perform some experiments to verify some of the logic operations. Breadboard A breadboard is used to make up temporary circuits for testing or to try out an idea. No soldering is required so it is easy to change connections and replace components.parts will not be damaged so they will be available to re-use afterwards. Breadboards have many tiny sockets (called 'holes') arranged on a 0.1" grid. The leads of most components can be pushed straight into the holes. ICs are inserted across the central gap with their notch or dot to the left. Wire links can be made with single-core plastic-coated wire of 0.6mm diameter (the standard size). Refer Figure 1.1 and Figure 1.2. ~ 1 ~

3 Figure 1.1: Breadboard Layout Figure 1.2: Sample Design using breadboard ~ 2 ~

4 ON-ON Single Pole, Double Throw = SPDT This switch can be on in both positions, switching on a separate device in each case. It is often called a changeover switch. Example: SPDT switch can be used to switch on a red lamp in one position and a green lamp in the other position. A SPDT toggle switch may be used as a simple on-off switch by connecting input to COM and switch places between A or B terminals as shown in Figure 1.3. A and B are interchangeable so switches are usually not labeled. Refer Figure 1.4. Figure 1.3: Toggle Switch (SPDT) Figure 1.4: Toggle Switch configuration ~ 3 ~

5 Integrated Circuits (ICs) IC pins are numbered anti-clockwise around the IC starting near the notch or dot. The diagram shows the numbering for 8-pin and 14-pin ICs, but the principle is the same for all sizes. Refer Figure 1.5. Figure 1.5: Integrated Circuits (ICs) Example (Refer Figure 1.6): Quad 2-input gates 7400 quad 2-input NAND 7403 quad 2-input NAND with open collector outputs 7408 quad 2-input AND 7409 quad 2-input AND with open collector outputs 7432 quad 2-input OR 7486 quad 2-input EX-OR quad 2-input NAND with Schmitt trigger inputs Figure 1.6: Integrated Circuit Layout ~ 4 ~

6 Figure 1.7: Integrated Circuit Layout and connection example ~ 5 ~

7 Light Emitting Diode (LED) LEDs emit light when an electric current passes through them. LEDs must be connected the correct way round, the diagram may be labelled a or + for anode and k or - for cathode. The cathode is the short lead and there may be a slight flat on the body of round LEDs. Inside the LED the cathode is the larger electrode (flag) (but this is not an official identification method). Figure 1.8: Light Emitting Diode Layout Resistors Resistors restrict the flow of electric current. The Unit is in ohm (Ω). Resistors may be connected either way round. Resistor values are normally shown using coloured bands. Each colour represents a number as shown in the table (next slide). Resistor values depends on colour code. Most resistors have 4 bands (Refer Figure 1.9): The first band gives the first digit. The second band gives the second digit. The third band indicates the number of zeros. The fourth band is used to shows the tolerance (precision) of the resistor, this may be ignored for almost all circuits. Figure 1.9: Resistor coloured bands ~ 6 ~

8 EXPERIMENT CAUTION 1. Use testpen screwdrivers to remove ICs from the breadboard. 2. Make sure the power cables are properly connected. ASK for technical assistance before switching the power on to the project. 3. Use multi-meters to check your voltage levels. 1. Refer to the data sheet for the 7404 IC. It contains six NOT gates. Wire one of them as follows: Figure 1.9 : NOT gate connections Note: V cc = +5V to pin 14 and GND = 0V to pin 7 of the IC 2. Create a truth table for a NOT gate in Table 1.1 (page 9), then verify the NOT operation by observing the LED and toggle switch conditions. Assume Logic 1 when there is 5V and Logic 0 when 0V. (Fill Table 1.1 of the results) 3. Refer to the data sheet for the 7432 IC. It contains four OR gates. Wire one of them as follows: Figure 1.10 : OR gate connection Note: V cc = +5V to pin 14 and GND = 0V to pin 7 of the IC 4. Create a truth table for an OR gate in Table 1.2 (page 9). Verify the OR operation by observing the LED and toggle switch conditions. Assume Logic 1 when there is 5V and Logic 0 when 0V. (Fill Table 1.2 of the results) ~ 7 ~

9 5. Refer to the data sheet for the 7408 IC. It contains four AND gates. Wire one of them as follows: Figure 1.11 : AND gate connection Note: V cc = +5V to pin 14 and GND = 0V to pin 7 of the IC 6. Create a truth table for an AND gate in Table 1.3 (page 9). Verify the AND operation by observing the LED and toggle switch conditions. Assume Logic 1 when there is 5V and Logic 0 when 0V. (Fill Table 1.3 of the results) 7. Construct the logic circuit as shown in Figure 1.12 below. Figure 1.12 : Logic Circuit a. Use THREE (3) toggle switches to represent inputs A, B and C. b. Use FOUR (4) LEDs to represent outputs W, X, Y and Z. Use ONE(1) 330 ohm resistor before ground. c. Construct the truth table in Table 1.4 (page 10). Make sure you identify your input and output names and the positions from MSB to LSB. ~ 8 ~

10 DKT122 ANSWER SHEET EXPERIMENT 1 : INTRODUCTION TO LOGIC GATES NAMA IC No. GROUP MATRIC No. DATE Table 1.1 : NOT gate Truth Table INPUT NAME(S) OUTPUT NAME(S) Verification chop/sign Table 1.2 : OR gate Truth Table INPUT NAME(S) OUTPUT NAME(S) Verification chop/sign Table 1.3 : AND gate Truth Table INPUT NAME(S) OUTPUT NAME(S) Verification chop/sign ~ 9 ~

11 EXPERIMENT 1 : INTRODUCTION TO LOGIC GATES NAMA DKT122 ANSWER SHEET IC No. GROUP MATRIC No. DATE Table 1.4 : Logic Circuit Truth Table INPUT NAME(S) OUTPUT NAME(S) Verification chop/sign 1. ASK for verification from the instructors 2. This answer sheet will be attached to your lab report. 3. Your lab report will consist of : a. This weeks lab expected learning outcome b. Descriptive information on task done c. Results (attached answer sheet) and observation d. Concluding remarks 4. Lab Report Dateline : 1 week after task end ~ 10 ~